A load hook for lifting gear is disclosed in U.S. Pat. No. 2,625,005, which includes a housing and a hook. The housing is formed as a cylindrical sleeve, the lower end of which is partially closed via an annular disc with a central opening. The opposite end of the sleeve is open. The housing is suspended in a conventional manner on a cable or a chain of the lifting gear. The hook has a curved hook part with a hook opening to receive a load lifting means, such as, e.g., a cable, a loop or a belt, and a shaft adjoining the hook part. The shaft is provided in the region of its upper end with a peripheral semi-circular groove and in the assembled condition is inserted into the central opening of the housing. In order to hold the shaft in the housing, a bearing ring is inserted into the housing from above and is supported on the annular disc, this bearing ring being provided with a central opening to receive the shaft and being provided on its upper inner edge with a quadrant-shaped contact surface. For assembly purposes the shaft can be inserted so far into the opening in the annular disc that the groove thereof lies over the support surface of the bearing ring. Then a ring divided into two 180-degree segments and having a fully circular cross-section is inserted into the groove from the sides and the shaft is moved downwards back through the opening so that the annular segments come to rest on the contact surface of the bearing ring. The dimensions of the groove in the ring and of the contact surface are selected in such a way that a snug fit is produced. In order to be able to rotate the hook with respect to the housing about the longitudinal axis of its shaft, roller bearing balls are disposed between the bearing ring and the annular disc, these balls rolling on the annular disc and in a running surface provided at the bottom in the bearing ring.
Furthermore, from the German laid-open document DE 102 36 408 A1 a suspension arrangement for a hook, in particular for hook blocks of lifting gear, is known. The hook again has a shaft which is suspended on a cross-piece which can pivot about a substantially horizontal axis. For this purpose the cross-piece is provided with a through bore transverse to its longitudinal direction, through which bore the free end of the shaft is inserted. In the region of the end of the shaft a peripheral, half-ring shaped groove is also provided which serves to receive a circlip. By means of the circlip the hook is supported on a bearing ring which is supported on the cross-piece via an axial ball bearing. The circlip has a fully-circular cross-section and is split at one point so that it can be mounted. Circlips of this type are conventionally used for securing the axial position of roller bearings. A quadrant-shaped contact surface for receiving the circlip is also provided in this case on the inner upper edge of the bearing ring.
Furthermore, from the German patent DE 32 20 253 C2 a further rotatable load hook for a hook block of a lifting gear is known. Also, in this case, the load hook has a hook shaft, the free end of which is guided through a through bore of a cross-piece of the hook block. In order to be able to support the hook shaft in a rotatable manner on the cross-piece an axial bearing is disposed on the cross-piece coaxial to the through bore. A retaining part in the form of a cylindrical pipe lies on the axial bearing, the retaining part being split in the middle for assembly purposes, being supported in an annular groove in the hook shaft and being held together in the installed position by a connecting sleeve. The connecting sleeve is secured in the longitudinal direction of the hook shaft via a spring ring which is mounted in a peripheral groove in the hook shaft. The load received by the hook is, therefore, carried into the cross-piece via the retaining part. For this purpose, the retaining part is supported in the annular groove of the hook shaft. The retaining part and the annular groove are formed in a specific manner in order to create a secure load hook with an increased service life. The annular groove is produced by a rolling process and, therefore, has a plastically deformed and strengthened surface. Furthermore, the annular groove has a cross-section which has edge regions with a small radius of curvature and a base region with a large radius of curvature. The base region with the large radius of curvature is almost flat. The retaining part in engagement with the annular groove is almost in the form of a cylindrical pipe and is slightly convex to correspond to the shape of the annular groove. The lower end thereof is adjoined by a flange region extending outwards approximately at a right angle, the retaining part lying on the axial bearing via this flange region. The supporting forces are diverted into the flange region in a manner corresponding to the shape of the retaining part for introduction into the axial bearing.